Advancements in catalysts for glycerol oxidation via photo-/electrocatalysis: a comprehensive review of recent developments

Abstract

The rise in demand for biomass as a renewable energy source is being seen as an alternative energy source to conventional fossil fuels. Blending of biodiesels and bioethanol in gasoline is the initial step towards complete utilization of biomass fuels. Glycerol is a byproduct generated in vast quantities during biodiesel production. Glycerol, on further oxidation, can produce several value-added products in conjunction with hydrogen (H₂) through photo-/electrocatalysis (PEC/EC). Valuable products from glycerol include 1,3-dihydroxyacetone, glyceraldehyde, tartronic acid, formic acid, and glyceric acid. Glycerol can be used as a feedstock in PEC/EC cells along with water. An intriguing strategy unfolds by combining the oxidation of biomass-derived compounds at the anode with the hydrogen evolution reaction taking place at the cathode, all contained within a biomass electrolysis or photo-reforming reactor. This approach enables the simultaneous production of high-value chemicals and hydrogen, while minimizing energy consumption and reducing CO₂ emissions. This review seeks to integrate essential insights into photo- and electro-assisted catalysis, with the objective of offering a holistic comprehension of the overall reaction mechanisms involved in the photo-/electrocatalytic oxidation of glycerol. At the same time, various transition metal-based photo-/electrocatalysts for glycerol valorization are reviewed and discussed in great detail. Moreover, this evaluation carefully examines the obstacles and possibilities for the advancement of photo-/electrocatalytic glycerol oxidation, aligning with future demands for sustainability in the global energy landscape.